The last Australopith?

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Splashing all over the science news this week is a host of revelations about Australopithecus sediba. This particular early human has been in an out of our shows since 2010, when Professor Lee Berger from the University of the Witswatersrand first published his discovery. What's important about these fossils is that, at almost two million years old, they are amazingly preserved, and they demonstrate characteristics of both australopthecines and the species Homo. Australopithecines are those early humans that had small brains, but could walk about some of the time on two legs - whereas Homo tends to have a larger brain and walk almost exclusively on two legs.

Publishing in the journal Science, it's been demonstrated that sediba has some of the features of both groups. There are other findings that put sediba somewhere in between the australopiths and homo: it had arched feet but quite ape-like heels and calves, it had cusped teeth which were large - but not as large as the usual australopith.

There are also differences from the earlier australopithecines in the shape of sediba's pelvis. The flat, flaring sections known as the Iliac blades are quite thick and vertically orientated, as you see in modern humans. But there aren't any indications that these changes were actually associated with having bigger-brained babies. So what the authors very cautiously posit is that sediba's hips were becoming more Homo-like through walking much more like Homo - and that bigger brains weren't required to drive certain changes in the pelvis.

Plus, this fossil may provide some much-sought answers about that mysterious early hominin from southeast Asia - Homo floresiensis (the hobbit).And you can hear more of that in a special half-hour interview with Professor Lee Berger on our website at thenakedscientists.com.